Apparatus and method for simultaneously winding two strands of wire on a bobbin

Abstract

An apparatus for winding two coils simultaneously on a bobbin, such as winding the two secondary coils of a linear variable differential transformer (LVDT), has a chuck or the like holding a bobbin. The chuck is rotated by a first motor. First and second wire guides move linearly in directions opposite to one another along the axis of rotation of the bobbin, and guide two strands of wire onto the rotating bobbin. The wire guides arrive simultaneously at the longitudinal center of the bobbin where the two strands of wire cross one another. The two wire guides are driven by two lead screws which rotate at identical speeds but in opposite directions to one another. The lead screws are driven by a second motor. The speeds of rotation of both motors are controlled by a computer, whereby the pitch pattern of the windings is determined by a computer program.

What is claimed is: 
     
       1. An apparatus for winding wire in coils on a bobbin, the apparatus comprising: means for rotating the bobbin;   first wire guide means for guiding a first strand of wire onto the rotating bobbin;   first carriage means for imparting reciprocating lateral motion to the first wire guide means, said motion being in a direction parallel with the axis of rotation of the bobbin;   second wire guide means for guiding a second strand of wire onto the rotating bobbin, and   second carriage means for imparting reciprocating lateral motion to the second wire guide means, said motion being in a direction parallel with the axis of rotation of the bobbin, the first and second wire guide means and the first and second carriage means jointly being adapted so that the respective motions imparted to the first and second carriage means are in opposite directions to one another and so that the first and second strands of wire cross one another while being wound on the bobbin each time the respective first and second carriage means move past the longitudinal center of the bobbin.   
     
     
       2. The apparatus of claim 1 wherein the means for rotating the bobbin comprise a rotating chuck driven by a first motor. 
     
     
       3. The apparatus of claim 2 wherein the means for rotating the bobbin further comprise a rotating tailstock which is also driven by the first motor. 
     
     
       4. The apparatus of claim 3 further including means for applying a force in a direction parallel with the axis of rotation of the bobbin against the rotating tailstock whereby the rotating bobbin is kept under tension. 
     
     
       5. The apparatus of claim 4 wherein the means for applying force is an air cylinder. 
     
     
       6. The apparatus of claim 2 wherein the first carriage means include a first wire guide carriage carrying the first wire guide means, a first rail on which the first wire guide carriage is mounted for lateral sliding motion, and a first lead screw rotated by a second motor and mounted to the first wire guide carriage to move the first wire guide carriage on the first rail, and wherein the second carriage means include a second wire guide carriage carrying the second wire guide means, a second rail on which the second wire guide carriage is mounted for lateral sliding motion, and a second lead screw rotated by the second motor and mounted to the second wire guide carriage to move the second wire guide carriage on the second rail, the first and second lead screws being rotated in opposite directions. 
     
     
       7. The apparatus of claim 6 further including computer means adapted for providing a programmed input into the second motor, whereby the speed of rotation of the first and second lead screws and thereby the lateral motions of the first and second wire guide carriages is controlled by a program so that the first and second wires wound on the bobbin have pitches of winding which are controlled by the program. 
     
     
       8. The apparatus of claim 7 wherein the computer means are also adapted for providing a controlled input into the first motor, whereby the speed of rotation of the first motor is controlled by the program. 
     
     
       9. The apparatus of claim 8 further comprising additional means for manually regulating the speed of the first motor. 
     
     
       10. The apparatus of claim 9 wherein the additional means comprise a potentiometer. 
     
     
       11. An apparatus for simultaneously winding two strands of wire on a bobbin, the apparatus comprising: a first motor operatively connected to means for rotating the bobbin;   first wire guide means for guiding a first strand of wire onto the rotating bobbin;   first carriage means for imparting reciprocating lateral motion to the first wire guide means, said motion being in a direction parallel with the axis of rotation of the bobbin;   a second motor operatively connected to the first carriage means for moving the first carriage means;   second wire guide means for guiding a second strand of wire onto the rotating bobbin, and   second carriage means for imparting reciprocating lateral motion to the second wire guide means, said motion being in a direction parallel with the axis of rotation of the bobbin, the second carriage means being operatively connected to and being moved by the second motor, the first and second wire guide means and the first and second carriage means jointly being adapted so that the respective motions imparted to the first and second carriage means are in opposite directions to one another and so that the first and second strands of wire cross one another while being wound on the bobbin each time the respective first and second carriage means move past the longitudinal center of the bobbin.   
     
     
       12. The apparatus of claim 11 wherein the means for rotating the bobbin include a chuck rotated by the first motor. 
     
     
       13. The apparatus of claim 12 wherein the means for rotating the bobbin further include a tailstock which is driven by the first motor. 
     
     
       14. The apparatus of claim 11 further including means for varying, in accordance with a predetermined program, the velocity of the reciprocating lateral motions of the first and second carriage means. 
     
     
       15. The apparatus of claim 14 wherein the means for varying, in accordance with a predetermined program, comprises a computer. 
     
     
       16. The apparatus of claim 11 further comprising first and second lead screws, each of the lead screws being operatively connected to the respective first and second carriage means to move said first and second carriage means, respectively, the lead screws being mounted to be rotated by the second motor at speeds which are identical to one another and in directions opposite to one another. 
     
     
       17. The apparatus of claim 16 wherein the second motor includes a rotating shaft which engages a timing belt, and wherein the same timing belt drives each of the first and second lead screws. 
     
     
       18. The apparatus of claim 16 further comprising first and second rail means, each rail means being adapted for slideably mounting the respective first and second carriage means. 
     
     
       19. An apparatus for simultaneously winding two strands of wire on a bobbin, the apparatus comprising: a first motor operatively connected to means for rotating the bobbin, said means including a chuck and a tailstock, each of which is adapted for holding the bobbin;   first wire guide means for guiding a first strand of wire onto the rotating bobbin;   a first fixedly mounted rail;   first carriage means for imparting reciprocating lateral motion to the first wire guide means, said motion being in a direction parallel with the axis of rotation of the bobbin, the first carriage means being slideably mounted on the first rail;   a first rotatably mounted lead screw operatively connected to the first carriage means for imparting the reciprocating lateral motion to the first carriage means;   a second motor operatively connected to the first lead screw for rotating the first lead screw;   second wire guide means for guiding a second strand of wire onto the rotating bobbin;   a second fixedly mounted rail;   second carriage means for imparting reciprocating lateral motion to the second wire guide means, said motion being in a direction parallel with the axis of rotation of the bobbin, the second carriage means being slideably mounted on the second rail, and   a second rotatably mounted lead screw operatively connected to the second carriage means for imparting the reciprocating lateral motion to the second carriage means, the second lead screw being rotated by the second motor in a direction opposite to the direction of rotation of the first lead screw, the first and second wire guide means and the first and second carriage means jointly being adapted so that the respective motions imparted to the first and second carriage means are in opposite directions to one another and so that the first and second strands of wire cross one another while being wound on the bobbin, each time the respective first and second carriage means move past the longitudinal center of the bobbin.   
     
     
       20. The apparatus of claim 19 further comprising means for varying the speed of rotation of the first and second lead screws in accordance with a predetermined program, whereby the lateral motions of the first and second carriage means are controlled in accordance with the predetermined program. 
     
     
       21. The apparatus of claim 20 wherein the means for varying comprise computer means. 
     
     
       22. The apparatus of claim 20 further comprising a timing belt connected to a rotating output shaft of the second motor, the timing belt driving the first and second lead screws. 
     
     
       23. The apparatus of claim 22 further comprising idler pulley means operatively engaging the timing belt for reversing the direction of rotation of the second lead screw relative to the direction of rotation of the first lead screw. 
     
     
       24. The apparatus of claim 21 wherein the first motor drives the tailstock. 
     
     
       25. The apparatus of claim 24 further including means for applying a force in a direction parallel with the axis of rotation of the bobbin against the rotating tailstock whereby the rotating bobbin is kept under tension. 
     
     
       26. The apparatus of claim 25 wherein the means for applying force is an air cylinder. 
     
     
       27. A process for winding wire coils on a bobbin, the process comprising: rotating the bobbin about its longitudinal axis;   moving a first wire guide laterally in a back and forth reciprocating motion relative to the rotating bobbin to guide a first strand of wire for winding on the bobbin, and   simultaneously with the moving of the first wire guide, moving a second wire guide laterally in a back and forth reciprocating motion relative to the rotating bobbin to wind a second strand of wire on the bobbin, the second wire guide being always moved in a direction opposite to the direction of moving the first wire guide, the first and second wires crossing one another substantially in the middle of the bobbin as said strands of wire are being wound on the bobbin.   
     
     
       28. The process of claim 27 wherein each of the steps of moving the first and second wire guides, respectively, comprises moving said wire guides at a speed which varies along the axis of rotation of the bobbin. 
     
     
       29. The process of claim 28 further comprising the steps of laying a layer of insulator material on each layer of wire deposited on the bobbin, said laying of the insulator material being performed substantially when the first and second strands of wire cross one another. 
     
     
       30. The process of claim 29 further comprising the steps of substantially halting the rotation of the bobbin, and of the movement of the first and second wire guides while the step of laying the insulator material is performed.